1. Field of the Invention
The present invention relates generally to irrigation control devices and more specifically to decoder-based irrigation control system including decoder units for coupling to actuator coil-controlled irrigation equipment.
2. Discussion of the Related Art
In decoder-based irrigation control systems, an irrigation controller sends signaling along a wire path to which one or more decoder devices are attached. Each decoder device monitors transmissions on the wire path and decodes this signaling to determine when to cause irrigation devices coupled thereto to be activated and deactivated. The decoder module typically includes circuitry formed on a printed circuit board located within a housing. Wiring from the decoder module housing must be coupled to the wiring of the wire path as well as coupled to one or more actuator devices each controlling the opening and closing of an irrigation rotor or valve. In one form, the rotor or valve is operated by a solenoid coil as is well known in the art. Likewise, during installation, the operator must provide and electrically connect two separate devices, a decoder module and an actuator coil module, to each other and to the control wire path. FIG. 1 illustrates a separate decoder module 102 and a coil unit 104 that are conventionally coupled together. For example, as illustrated in FIG. 2, for a solenoid activated rotor assembly 200, the coil module 104 is coupled (in part by a bracket 212 and retainer 214) to the parts of a selector valve assembly 202 (including a pressure regulator) attached to a casing assembly 204. The electrical wire inputs to the coil module 104 are then connected to the electrical wire outputs from the decoder module 102, while the electrical wire inputs to the decoder module 102 are coupled to the control wire path from the irrigation controller. Thus, a typical installation requires the connection of six wires to install the decoder module 102 and a coil module 104.
As is well known, in operation, a portion of a plunger (not shown) of the selector valve assembly 202 is disposed within the coil unit 104 while another portion is seated against a solenoid plunge port (not shown) within the selector valve assembly 202 in a normally closed position. In this position, high pressure water flow from a main water control valve (not shown) located within a main control valve portion 206 of the device is flowed up high pressure water line 208 into the selector valve assembly 202 and its regulator and is prevented from further movement by the normally closed position of the plunger against the solenoid port in the selector valve assembly 202. This results in a back pressure that causes the main water control valve to close. In response to signals from the decoder module 102, the coil module 104 causes the actuation of the plunger to move it off of (or unseat from) the solenoid plunge port allowing the high pressure flow in the high pressure line 208 to flow through the selector valve assembly 202 (and its pressure regulator), which relieves the back pressure and allows water to flow through the main control valve and to a pop-up sprinkler device, i.e., the main water control valve is opened. The pop-up sprinkler device is located within the casing assembly 204 and extends upwardly due to the water pressure through a top portion of the casing assembly 204. The high pressure flow exits the selector valve assembly 202 down through a discharge flow line 210 which terminates within the casing assembly 204 at a location downstream of the main water control valve.